A pedestrian crosses a street inundated by floodwaters from Tropical Storm Harvey. Picture: Charlie Riedel/AP

Houston - When Adrielle Smith is old enough, what a story her parents will share about the day she was born.

That happened early Monday in Houston, where historic flooding caused by Hurricane Harvey left Greg and Andrea Smith, who had gone into labour, trapped in their apartment and unable to make contact with either 911 or the Coast Guard.

As first reported by People, the soon-to-be parents - both doctors, coincidentally - made preparations for a risky at-home delivery, though they had no medical supplies and no specific specialisation in obstetrics.

(He's a paediatric anaesthesiologist. She works in geriatrics. A doctor friend with experience delivering babies was prepared to talk Greg through the procedure via Skype, People's Susan Keating reported.)

Several other medical professionals also live in the Smiths' apartment community. A request for help went out to the entire complex on Sunday, and before long help arrived with equipment and supplies.

As Greg Smith's mother boiled the instruments to sterilise them, a decision was made to move the delivery to a second-floor apartment, away from the floodwaters.

Someone in the group sent a message to an acquaintance whose father lives near a fire station. He alerted the firefighters and, unknown to the Smiths, a rescue mission was hatched.

As Greg Smith prepared for the delivery, a dump truck came lumbering down the street. He ran outside to hail the people inside.

They responded, "We're here for you," he told People.

What happened next will be remembered as among the devastating storm's most poignant moments, a testament to human will and compassion.

One by one, the Smiths' neighbours clasped hands and formed a chain in the waist-high water, carefully guiding Andrea and Greg to the truck's bed, where they climbed on board and were driven to the hospital.

Neighbour Molly Akers, who captured the moment on video, said on Facebook, "Moments like these are incredibly precious and remind me of all the good in the world."

For the Smiths, their good fortune seemed like divine intervention. Having twice miscarried, according to People, they'd become intently focused on their faith with hopes of getting pregnant again.

The baby girl was born at 1:59am and later assigned to the intensive care unit with unspecified medical issues. Greg Smith told People that the child is healthy and that he and his wife are relieved to be in the hospital, where she can receive proper care.

"Everything about this pregnancy we said is God's will," he told People. "That's why her name is Adrielle. It means she belongs to God."